An aftertreatment system is associated with an engine system. The aftertreatment system is configured to treat and reduce oxides of nitrogen (NOx) present in an exhaust gas flow, prior to the exhaust gas flow exiting into the atmosphere. In order to reduce NOx, the aftertreatment system may include a reductant delivery module, a reductant injector, and a Selective Catalytic Reduction (SCR) module.
The aftertreatment system includes oxidation catalysts, such as a Diesel Oxidation Catalyst (DOC) unit associated therewith. For example, the DOC unit may be used to create a desired ratio of Nitric Oxide (NO) to Nitrogen Dioxide (NO2) in the engine's exhaust gas flow that enhances NOX reduction within the SCR module provided downstream of the DOC unit. In another example, the DOC unit can be used to increase an overall amount of NO2 in the exhaust gas flow passing through a Diesel Particulate Filter (DPF) unit to lower a combustion temperature of particulate matter trapped in the DPF unit, and thereby enhance passive regeneration of the DPF unit.
Over a period of time, active catalytic materials present on the oxidation catalyst of the DOC unit, which may include precious materials such as platinum, rhodium, and/or palladium, may agglomerate and become less active, thereby affecting a performance metrics of the oxidation catalyst. Further, an accumulation of materials, such as particles of lubricating oil, may also affect the performance of the oxidation catalysts. A reduction in performance metrics of the oxidation catalyst may affect an overall operation of the aftertreatment system, which is not desirable. Therefore, it is necessary to test the performance of the oxidation catalysts at predetermined intervals in order to make sure that the oxidation catalyst is performing as intended.
Known solutions of testing the catalyst include heaters that are configured to heat a gas which is then flown over the catalysts. In another example, as described in U.S. Pat. No. 3,667,914, the catalyst is heated in an electric furnace. Further, a predetermined exhaust gas mixture or mixtures is passed through the catalyst at a desired test temperature. A pressure drop measurement is then made across the catalyst in order to determine a degradation of the catalyst bed. However, these solutions are expensive and time consuming Further, in some situations, the heating of the catalyst or passage of the heated gas may alter one or more properties of the catalyst and lead to a degradation thereof.